All libcalls should be considered to be GC-leaf functions.

Summary:
It is possible for some passes to materialize a call to a libcall (ex: ldexp, exp2, etc),
but these passes will not mark the call as a gc-leaf-function. All libcalls are
actually gc-leaf-functions, so we change llvm::callsGCLeafFunction() to tell us that
available libcalls are equivalent to gc-leaf-function calls.

Reviewers: sanjoy, anna, reames

Reviewed By: anna

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D35840

llvm-svn: 309291

1 files changed, 10 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 74610613001..805d7155ec7 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1832,7 +1832,8 @@ unsigned llvm::replaceDominatedUsesWith(Value *From, Value *To,
   return ::replaceDominatedUsesWith(From, To, BB, ProperlyDominates);
 }
 
-bool llvm::callsGCLeafFunction(ImmutableCallSite CS) {
+bool llvm::callsGCLeafFunction(ImmutableCallSite CS,
+                               const TargetLibraryInfo &TLI) {
   // Check if the function is specifically marked as a gc leaf function.
   if (CS.hasFnAttr("gc-leaf-function"))
     return true;
@@ -1846,6 +1847,14 @@ bool llvm::callsGCLeafFunction(ImmutableCallSite CS) {
              IID != Intrinsic::experimental_deoptimize;
   }
 
+  // Lib calls can be materialized by some passes, and won't be
+  // marked as 'gc-leaf-function.' All available Libcalls are
+  // GC-leaf.
+  LibFunc LF;
+  if (TLI.getLibFunc(CS, LF)) {
+    return TLI.has(LF);
+  }
+
   return false;
 }